Particle assemblies have been formed by others during the preparation of synthetic opals, photonic materials, and other materials. Colloidal crystals, ceramics, synthetic opals, and photonic materials have been formed from assemblies of spherically symmetric particles.
The structures are typically low information, meaning that little information is required to specify the placement of all components in a structure. For colloidal crystals, the typical amount of information is only two or three parameters. For example, close packed arrays of spheres, all spheres having the same composition, have been formed using conventional methods. The particles were densely packed and consisted only of particles with the same size and material. Other close-packed particle aggregates have been formed using emulsion techniques.
However, new approaches are required to produce more complex particle assemblies, including colloidal assemblies with more complex compositions and structures. To our knowledge, techniques do not yet exist for creating site-specific chemistry at any desired location on individual colloidal particles.